Basically for a professional website, It costs reach about 500 USD. You needs to purchase Domain, Hosting, Theme, Plugin and Developer Charge..
Domain and Hosting costs about 100 of dollars, Theme average cost 60 dollar, Plugin costs 200 or more as per requirements. And Developer charge about 200-250 USD
Some developer do with USD 5 but a professional developer won't agree with 5 USD as developing a website